On the impact of large angle CMB polarization data on cosmological parameters

Abstract

(abridged) We study the impact of the large-angle CMB polarization datasets publicly released by the WMAP and Planck satellites on the estimation of cosmological parameters of the $\Lambda$CDM model. To complement large-angle polarization, we consider the high-resolution CMB datasets from either WMAP or Planck, as well as CMB lensing as traced by Planck. In the case of WMAP, we compute the large-angle polarization likelihood starting over from low-resolution frequency maps and their covariance matrices, and perform our own foreground mitigation technique, which includes as a possible alternative Planck 353 GHz data to trace polarized dust. We find that the latter choice induces a downward shift in the optical depth $\tau$, of order ~$2\sigma$, robust to the choice of the complementary high-l dataset. When the Planck 353 GHz is consistently used to minimize polarized dust emission, WMAP and Planck 70 GHz large-angle polarization data are in remarkable agreement: by combining them we find $\tau =0.066_{-0.013}^{+0.012}$, again very stable against the particular choice for high-$\ell$ data. We find that the amplitude of primordial fluctuations $A_s$, notoriously degenerate with $\tau$, is the parameter second most affected by the assumptions on polarized dust removal, but the other parameters are also affected, typically between $0.5$ and $1\sigma$. In particular, cleaning dust with \planck's 353 GHz data imposes a $1\sigma$ downward shift in the value of the Hubble constant $H_0$, significantly contributing to the tension reported between CMB based and direct measurements of $H_0$. On the other hand, we find that the appearance of the so-called low $\ell$ anomaly, a well-known tension between the high- and low-resolution CMB anisotropy amplitude, is not significantly affected by the details of large-angle polarization, or by the particular high-$\ell$ dataset employed.

19 pages, 4 figures, 3 tables

References in corpus (3)

• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• Model-independent evidence in favor of an end to reionization by z~6
• A physical model for the evolving UV luminosity function of high redshift galaxies and their contribution to the cosmic reionization

Cited by in corpus (4)

• The state of the dark energy equation of state circa 2023
• Inference of the optical depth to reionization from low multipole temperature and polarisation Planck data
• Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz
• Accurate and efficient likelihood modeling for large-scale CMB data